Refrigerator appliances generally include a compressor. During operation of the refrigerator appliance, the compressor operates to provide compressed refrigerant. The refrigerator appliance utilizes such compressed refrigerant to cool a compartment of the appliance and food items located therein.
Certain refrigerator appliances include a reciprocating compressor that compresses refrigerant by sliding a piston within a chamber. Reciprocating compressors can include a piston mounted to a crankshaft. As the crankshaft turns, the piston slides within the chamber in order to compress refrigerant. However, the large number of moving parts associated with the piston and crankshaft can generate relatively large friction forces. Such friction can result in poor efficiency and negatively affect performance of the refrigerator appliance.
Recently, linear compressors have been used to compress refrigerant in refrigerator appliances. Linear compressors can include a piston and a driving coil. The driving coil receives a current in order to generate a force that slides the piston backward and forwards within a chamber to compress refrigerant. However, such linear compressors can require active control for every piston stroke in order to stop motion of the piston at either end of the piston's displacement. Such control can be complex, expensive, and inefficient.
In certain linear compressors, the piston is mounted to a spring that urges the piston towards a default position. In such a configuration, the piston oscillates from the default position with an amplitude that depends on the magnitude and frequency of force applied by the driving coil to the piston. By adjusting the strength of the driving coil's force and the frequency of application of such force, the piston can slide within the chamber at a resonant frequency in which the amplitude of the piston's displacement can be maximized for the force applied to the piston. However, using such mechanical springs can be inefficient because such mechanical springs have fixed spring constants.
Accordingly, a linear compressor with features for operating at a resonant condition would be useful. In particular, a linear compressor with features for operating at a resonant condition without mechanical springs would be useful. Further, a linear compressor with features for operating at a resonant condition without complex controls would be useful.